Insights of electronic structures, mechanical properties and thermal conductivities of TM5SiB2 (TM=V, Nb, and Ta) MAB phases

The electronic, elastic, and thermal properties of TM5SiB2 (TM = V, Nb, and Ta) MAB phases are calculated herein using first-principles calculations. The obtained electronic structures show that there are p-d hybridizations between B, Si, and TM atoms, and TM-B and TM-Si bonds are formed by the electrons transfer between TM and B, TM and Si. Elastic Modulus and elastic Anisotropy Index, three-dimensional surface construction, and two-dimensional projection are used to discuss the elastic anisotropy, and the results show that these TM5SiB2 MAB phases are anisotropic in elastic modulus with the order of V5SiB2 > Nb5SiB2 > Ta5SiB2. Besides, the Debye temperature and sound velocity of these TM5SiB2 are also analyzed. The thermal conductivities are obtained, and the thermal conductivity is also anisotropic and in the same order as elastic modulus.